I have to say a few words about the Sacred Band infantry...

These guys are nothing short of awesome. They are armored like turtles, they are almost completely immune to missiles (including pila), and, provided that their flanks are guarded, they will advance across the battlefield in one indestructible wall of desolation, mowing down any unit unfortunate enough to stand in their way.
They are great vs Romans (pre- or post-marian) and Egyptians. Conveniently enough, those are usually the only factions able to reach the superpower status, and Sacred Band is able to smash them. Carthaginian cavalry is of course still important (specifically, the Longshields), but its role is mostly to protect the SB flanks and finish off routers and waverers, while SB does most of the heavy lifting.
Sacred Band Cavalry on the other hand, is rather underwhelming: top level stables and 2-turn production cycle for something that is only marginally better than Longshields. Nah, might as well make an Armoured Phant to put the fear of Baal into the hearts of Romans.